On delete set null...

Simpor · **Joined:** Wed Oct 11, 2006 4:54 am **Posts:** 5

Hi,

I have a question which I can't find the answer to.

I have two tables. A and B
A is the parent and can have a B.
B is not aware of which A has it.

I have set up so that everything works the way I want except for one thing. I want to be able to delete a B and when I do that, the reference in A should be set to null.

In other words:
a (a1) has a b (b1)
I delete b1
a1 has no b1, the field b is set to null for a1.

It's very easy to do this in MySQL Query browser. Just set the foreign key in table A to (on delete set null).

But is there a way that hibernate can generate the schema automatically?
I'm using the following xml for the reference in table A.

Code:

<many-to-one name="b" column="b_id" class="B" cascade="none" fetch="join" not-null="false" lazy="false"/>

And this generates a foreign key reference in table A, which I want to include a "ON DELETE SET NULL".

Hope that my example describes what I want to do.

Simpor · **Joined:** Wed Oct 11, 2006 4:54 am **Posts:** 5

so hibernate does not support this?

Sounie · **Posted:** Fri Feb 06, 2009 7:44 am

From your description it sounds as though the A object has an ownership relationship with the B object, so it might make sense to have all access to the B object go via it's owner. Then you could move the deletion/removal responsibility into object A.

This is based on the assumption that objects of type B cannot exist without belonging to an object of type A.

--
Stephen Souness

littypreethkr · **Posted:** Fri Feb 06, 2009 9:29 am

Nope this is not supported. See this feature:
http://opensource.atlassian.com/project ... e/HHH-2707

Please vote for it so that it gets implemented.